Support for resistance wiring



Patented Aug. 26, 1924.

UNITED STATES FREDERICK W. MOFFAT, OF WESTON, ONTARIO, CANADA.

SUPPORT FOR RESISTANCE WIRING.

Application filed January 19, 1924. Serial No. 687,231.

To all, whom it may concern:

Be it known that I, FREDERICK W. Mor- FAT of the town of Weston, in the county of York, Province of Ontario, Canada, a Subject of the King of Great Britain, have invented certain new and useful Improvements in Supports for Resistance Wiring, of which the following is a specification.

This invention relates to devices for supporting coiled resistance wiring and more particularly to supports adapted to permit free radiation. Heretofore it has been common practice to support coiled resistance wiring at a number of points intermediate the ends of the coil. This arrangement permits the coil to sag intermediate its supports and make a short circuit. In my United States Patent No. 1,413,678, dated the th day of April, 1922, I show means for externally engaging the coiled resistance wiring to reduce the length of span between the supports but these means are inadequate in large ovens and furnaces where ver high temperatures are attained. The ob ect of my present invention is to provide a resistance support which will overcome the above objectionable features, that will permit free radiation and that will leave a sufiicient length of the resistance wiring entirely exposed between its external supports.

I attain my objects b means of the constructions hereinafter escribed and illustrated in the accompanying drawings in which- Fig. 1 is a side elevation of my improved support with supporting cores shown in position in a coiled resistance which is externall supported in supporting bars, one of the atter being shown in end elevation while two are shown in section;

Fig. 2 a cross section on the line 2-2 in Fig. 1 showing a supporting bar and a portion of an ad acent bar in side elevation, a portion of a bar being shown in vertical section to show the end elevation of my improved support Fig. 3 a perspective view of my improved internal support; and

Fig. 4 a side elevation of a modified form of support.

In the drawings like numerals of reference indicate corresponding parts in the difl'erent figures.

The supports 1 are formed of bars of any insula tin material and are suitably an ranged within an oven or a. furnace to carry the heatin element 2. The latter is helically coiled and strung on the supporting bars as follows. Each support is provided with a plurality of transverse bearings 3 and each bearing is provided with a plurality of spaced shoulders 4. These shoulders extend longitudinally of the axis of the helical heating element 2 and are extended laterally from each side of the bar 1. The coils of the element are externally engaged by the shoulders. The spaces between the latter thus permit free radiation from the heating element.

It is obvious that the coils of the element, when carried horizontally, tend to sag intermediate their supports, particularly when heated to a high temperature. This sometimes caused short circuits or the breakage of the coils and the above mentioned spaced shoulders were provided to overcome this objectionable feature. This construction forms the subject matter of the hereinbefore mentioned patent and accomplishes its purpose when used for supporting small heating elements such as used in ovens for domestic stoves and the like.

In large ovens or furnaces using very large elements attainin r very high temperatures the shoulders 4 do not provide sufficient support for the coiled elements. To overcome this I provide cores or internal supports 5, of insulating material, which extend axially through the helical heating element. These internal supports extend substantially from one external support to another external support. The preferable arrangement is to extend each internal support from the center of one external support to the center of the adjacent external support so that the internal supports break joint with the external supports. To permit free radiation of the heating element the cross sections of the cores 5 are so shaped as to prevent their full surfaces engaging the inner sides of the helical element. In other words it is desirable to provide longitudinal ggooves 6 between the helices and the core. his is accomplished by forming longitudinally spaced ribs 7 on each core, these ribs being adapted to only engage the inner sides of the helices on longitudinal lines of very small surface. areas.

With this construction the spans of coiled heating element between the ad'acent external supports 1 are supported y the internal supports 5. This is clearly .illustrated in Fig. 1 in which one internal support is omitted to indicate the average sag of an unsupported span of heating element. The internal supports or cores thus entirely eliminate the strain on the heating element while the efficiency of the latter is not reduced.

As shown in Fig. 4 a helically ribbed support may be employed for the straight ribbed su port shown in the other views.

Vhat I claim is 1. The combination with a horizontally arranged helical electric heating element, and a plurality of external supports for said element, of an internal support extending axially through the element.

2. The combination with a horizontally arranged helical electric heating element, of a plurality of external supports for said element. of an internal support extending axially through the element and provided with spaced ribs adapted to engage the inner sides of the helices of the element,

3. The combination with a horizontally arranged helical electric heating element,

and a plurality of supports for said element, each support having a plurality of spaced shoulders for externally engaging the helices of the element, of an internal support extending axially through the element.

4. The combination with a horizontally arranged helical electric heating element, and a plurality of supports for said element. each support having a plurality of spaced shoulders for externally engaging the helices of the element, of an internal support extending axially through the element and provided with spaced ribs adapted to engage the inner sides of the helices of the element.

5. The combination with a horizontally arranged helical electric heating element, and a plurality of external supports for said element, of an internal sup ort for the element extending substantial y from one ex ternal support to another.

6. The combination with a horizontally arranged helical electric heating element, and a plurality of external supports for said element, of an internal support extendin axially through the element and provided with spaced ribs adapted to engage the inner sides of the helices, the internal support extending substantially from one external su port to another.

l. The combination with a horizontally arranged helical electric heating element, and a plurality of supports for said element, each support having a plurality of spaced shoulders for externally engaging the helices of the element, of an internal su port for the element extending substantially from one external support to another.

8. The combination with a horizontally arranged helical electric heating element, and a plurality of external supports for said element, of a. plurality of internal supports extending axially through the element, the internal supports being adapted to break joint with the external supports,

Signed at Toronto, Canada, this 10th day of January, 1924.

FREDERICK W. MOFFAT. 

